Johnny Depp
James 'Whitey' Bulger
Joel Edgerton
John Connolly
Julianne Nicholson
Marianne Connolly
Dakota Johnson
Lindsey Cyr
Kevin Bacon
FBI Agent Charles McGuire
Benedict Cumberbatch
Billy Bulger
Peter Sarsgaard
Brian Halloran
Juno Temple
Deborah Hussey
Jesse Plemons
Kevin Weeks
David Harbour
John Morris
Adam Scott
FBI Agent Robert Fitzpatrick
Corey Stoll
Fred Wyshak
Bill Camp
John Callahan
Mark Mahoney
Mickey Maloney
Brad Carter
John McIntyre
Scott G. Anderson
Tommy King
Lonnie Farmer
DEA Agent Eric Olsen (Interrogator)
Mary Klug
Mom Bulger
Erica McDermott
Mary Bulger
Luke Ryan
Douglas Cyr
Owen Burke
Buddy Leonard
Lewis D. Wheeler
Jeremiah O'Sullivan
Billy Meleady
Joe Cahill
Jamie Donnelly
Mrs. Cody
David De Beck
Roger Wheeler
Gary Galone
State Captain
Rory Cochrane
Stephen Flemmi
James Russo
Agent Scott Gariola
Jeremy Strong
Josh Bond
Danae Nason
McGuire's Secretary
Bretton Manley
Young Boy
Berglind Jonsdottir
Anna Bjornsdottir
David Conley
Officer Flynn
Ciaran Crawford
Irish Nationalist
Thomas Philip O'Neill
FBI Wire Tech
Joey Vacchio
Joey, Big Italian
Bill Haims
Gennaro Angiulo
Anthony Molinari
Charlie McTiernan
Declan Mulvey
Charlie's Friend
Bates Wilder
Agent James
Marc Carver
Dick Lehr
Richard Donelly
Gerard O'Neill
Brian A. White
Prisoner
Peter Morse
FBI Agent
Tom Kemp
Father Mackey
Patrick M. Walsh
Michael Donahue
Naheem Garcia
DEA Agent
Kathryn A. Beauchamp
Nurse
Stephen Curran
Drug Dealer
Darin X.L. MacEachern
Drug Dealer
Cary 'Big Shug' Guy
Drug Dealer
Sean Malone
Crook
Jack Neary
Barman
Jimmy Joe Maher
Boot Shop Owner
Forry Buckingham
World Jai Alai Chairman
Danny DeMiller
Porthole Bartender
Michael F. Murphy
Porthole Customer
Alexander Cook
DEA Agent Dan Doherty
Ava Cooper
Little Mary Bulger
Stella Cooper
Kathleen Bulger
Arthur Hiou
Driver
Todd Ryan Jones
Charlie's Friend
Julie Ann Dawson
Floor Dancer (uncredited)
Fergaledgar
Trevor Williams (uncredited)
Robert Walsh
Sr. FBI Official (voice)
W. Earl Brown
John Martorano
Jim Powers
The Mayor
Jeff Kamps
Walker
Susan Garfield
Press Photographer
Colleen Kelly
Marion Hussey (uncredited)